Connector

ABSTRACT

A connector having a plug connected to an antenna through a coaxial cable and a receptacle. The plug includes a cylindrical shell, a pin contact, and an insulative pin contact holder provided inside the shell. The receptacle includes a first receptacle housing having a shell-receiving hole and a second receptacle housing provided inside the shell-receiving hole and having a pin contact-receiving hole. A first protrusion is formed in a distal end of the pin contact holder. A first reentrant in which the first protrusion is to be fitted is formed in a distal end of the second receptacle housing. The present invention can prevent the connection of external antennas of other manufacturers to the receptacle because the first protrusion and first reentrant are specified in shape. Also, the plug can be readily connected to the receptacle because the plug can be connected to the receptacle independently of the posture of the plug.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is based upon and claims the benefit of priorityfrom the prior Japanese Patent Application No. 2003-155693 filed on May.30, 2003, the entire contents of which is incorporated herein byreference.

[0002] 1. Field of the Invention

[0003] The present invention relates to a connector. More specifically,it relates to a connector for use in a notebook-sized personal computerand connecting to an external antenna for wireless LAN(Local AreaNetwork), for example.

[0004] 2. Background of the Invention

[0005] Conventionally, portable electronic systems adopting the wirelessLAN, such as notebook-sized personal computers (hereinafter referred toas notebook-sized PCs) and Personal Digital Assistants (PDA) have beenused at offices, homes, and the like. Such electronic systems allowusers to connect to broadband routers from any places by wireless and toaccess the Internet freely.

[0006] An electronic system as described above is provided with, forexample, an internal antenna for transmitting and receiving electricwaves inside a housing. In addition, the housing is provided with acoaxial connector having a switching function in order to furtherincrease the receiving efficiency thereof. Accordingly, when it isdifficult to transmit and receive electric waves through the internalantenna, the coaxial connector is connected to the external antenna toswitch from the internal antenna to the external antenna. Therefore,electric waves can be transmitted and received through the externalantenna.

[0007] Wireless LAN like this is standardized under IEEE 802.11a byInstitute of Electrical and Electronic Engineers (IEEE). Morespecifically, Federal communications commission (FCC) defines thatmanufacturers shall customize connectors for wireless LAN for electronicsystems to transmit and receive electric waves in a frequency rangearound 5.2 GHz used for high-speed wireless LAN. In other words, it isdefined that connectors for antennas shall each have a maker-specificstructure so as to prevent any external antennas of other manufacturersfrom being connected to the connectors.

[0008] The above-described definition presented by FCC is not applied tointernal antennas, but the FCC definition is applied to connectors towhich external antennas are to be connected. Therefore the connectorsmust be customized.

[0009] In order to solve the problem, there has been known a connectorhaving a key and a key groove (see JP-A-9-306603). More specifically,the connector has a plug connected to an external antenna and areceptacle formed with a plug-in opening in which the plug is to beplugged. Here, the plug has the key provided in its distal end, and thereceptacle has the key groove provided in the plug-in opening thereof.According to the configuration, the key of the plug is fitted in the keygroove of the receptacle, which makes it impossible to connect the othermanufacturer's plug to the receptacle. The plug and receptacle can bereliably connected with each other by screwing the coupling cap nut thatthe plug holds in the external thread formed in the periphery of thereceptacle.

[0010] However, it is difficult to identify the location of the keygroove in a connector as described above when the receptacle is mountedin a place which is difficult for a user to see. Especially, in recentyears notebook-sized PCs have been advancing in slimming the housing andaccordingly in downsizing the connectors and as such, it has been moredifficult to identify the location of the key groove. Therefore, theplug couldn't be connected to the receptacle readily.

[0011] Furthermore, when a coaxial cable is connected to the side faceof the plug, i.e. when the connector is a so-called right angleconnector (and also referred to as an L-shaped connector) in which thedirection of the plug plugged in and the extending direction of thecoaxial cable intersect at right angles, the posture of the plug islimited by the provision of the key and key groove when the plug isplugged. Accordingly, the connector may not be able to obtain goodusability because the extending direction of the coaxial cable is alsolimited.

[0012] The above-described definition by FCC is not limited to thecombination of the key and key groove as a maker-specific structure.

SUMMARY OF THE INVENTION

[0013] Therefore, in order to solve the above-described problems, anobject of the invention is to provide a connector which does not allowany external antennas of other manufacturers to be connected to thereceptacle and allows the plug to be readily connected to thereceptacle.

[0014] In order to achieve the object, configurations as described beloware adopted in the invention.

[0015] (1) A connector comprising:

[0016] a plug connected to an antenna through a coaxial cable; and

[0017] a receptacle which said plug is to be put in and removed from;

[0018] wherein said coaxial cable including an inside conductorextending in its axial direction, and an outside conductor providedoutside the inside conductor and extending in its axial direction;

[0019] wherein said plug including a cylindrical shell connected to theoutside conductor of said coaxial cable, a pin contact connected to theinside conductor of said coaxial cable, and an insulative pin contactholder provided inside the shell for holding the pin contact on acentral axis of the shell;

[0020] wherein said receptacle including a first receptacle housinghaving a cylindrical shell-receiving hole in which the shell of saidplug is to be plugged, and a second receptacle housing provided insidethe shell-receiving hole and having a pin contact-receiving hole inwhich the pin contact is to be plugged;

[0021] wherein a first protrusion is formed in a distal end of the pincontact holder; and

[0022] wherein a first reentrant in which the first protrusion is to befitted is formed in a distal end of the second receptacle housing.

[0023] The connector may be used for compact systems adopting thewireless LAN. For example, the connector with an external antenna may beused in a high-speed wireless LAN standardized under IEEE 802.11a.

[0024] The antenna may be, for example, an external antenna which isprovided outside a system in which the connector is mounted. The antennamay be, for example, a wire antenna or a whip antenna. Thetransmitter-receiver terminal of the antenna are connected to the insideconductor of the coaxial cable, and the ground terminal thereof isconnected to the outside conductor of the coaxial cable.

[0025] The inside conductor of the coaxial cable may be, for example, acore wire, and may be fixed on the proximal end side of the pin contactby solder. In addition, the outside conductor of the coaxial cable maybe, for example, a braided wire and may be pinched on the proximal endside of the cylindrical shell thereby to be fixed.

[0026] The connecting portion of the plug and coaxial cable may becovered with an insulating protective cover. In this case, theprotective cover may be grasped thereby to put the plug in thereceptacle and remove the plug from the receptacle.

[0027] Grooved notches may be formed on its distal end side and proximalend side of the periphery of the pin contact holder respectively. Thegrooved notches may be engaged to the cylindrical shell to hold the pincontact holder in the cylindrical shell.

[0028] Inside the second receptacle housing, a fixed contact and anelastically-deformable and movable contact urged toward the fixedcontact maybe provided. In this case, the pin contact is inserted in thepin contact-receiving hole. Thus, the distal end of the pin contactenters between the movable contact and the fixed contact and presses themovable contact to separate the movable contact from the fixed contact.In contrast, when the pin contact is withdrawn from the pincontact-receiving hole, the movable contact abuts the fixed contactthereby to be electrically connected to the fixed contact. Accordingly,the receptacle has a switching function.

[0029] In addition, the receptacle may be disposed on a printed wiringboard and fixed to a ground pattern on the board by solder.

[0030] According to the invention of (1), the first protrusion of thepin contact holder is fitted in the first reentrant of the secondreceptacle housing, thereby to connect the plug to the receptacle. Thus,the first protrusion and the first reentrant are specified in shape sothat the connector can prevent any external antennas of othermanufacturers from being connected to the receptacle.

[0031] In addition, the plug can be connected to the receptacleindependently of the posture of the plug because it is not required tocombine a key and a key groove like conventional cases. On this account,the plug can be readily connected to the receptacle.

[0032] (2) A connector comprising:

[0033] a plug connected to an antenna through a coaxial cable; and

[0034] a receptacle which said plug is to be put in and removed from;

[0035] wherein said coaxial cable including an inside conductorextending in its axial direction, and an outside conductor providedoutside the inside conductor and extending in its axial direction;

[0036] wherein said plug including a cylindrical shell connected to theoutside conductor of said coaxial cable, a pin contact connected to theinside conductor of said coaxial cable, and an insulative pin contactholder provided inside the shell for holding the pin contact on acentral axis of the shell;

[0037] wherein said receptacle including a first receptacle housinghaving a cylindrical shell-receiving hole in which the shell of saidplug is to be plugged, and a second receptacle housing provided insidethe shell-receiving hole and having a pin contact-receiving hole inwhich the pin contact is to be plugged;

[0038] wherein a first reentrant formed in a distal end of the pincontact holder; and

[0039] wherein a first protrusion which the first reentrant is to befitted in is formed in a distal end of the second receptacle housing.

[0040] The connector may be used for compact systems adopting thewireless LAN. For example, the connector with an external antenna may beused in a high-speed wireless LAN standardized under IEEE 802.11a.

[0041] The antenna may be, for example, an external antenna which isprovided outside a system with the connector mounted therein. Theantenna may be, for example, a wire antenna or a whip antenna. Thetransmitter-receiver terminal of the antenna are connected to the insideconductor of the coaxial cable, and the ground terminal thereof isconnected to the outside conductor of the coaxial cable.

[0042] The inside conductor of the coaxial cable may be, for example, acore wire, and may be fixed on the proximal end side of the pin contactby solder. In addition, the outside conductor of the coaxial cable maybe, for example, a braided wire and may be pinched on the proximal endside of the cylindrical shell thereby to be fixed.

[0043] The connecting portion of the plug and coaxial cable may becovered with an insulating protective cover. In this case, theprotective cover may be grasped thereby to put the plug in thereceptacle and remove the plug from the receptacle.

[0044] Grooved notches may be formed on its distal end side and proximalend side of the periphery of the pin contact holder respectively. Thegrooved notches may be engaged to the cylindrical shell to hold the pincontact holder in the cylindrical shell.

[0045] Inside the second receptacle housing, a fixed contact and anelastically-deformable and movable contact urged toward the fixedcontact may be provided. In this case, the pin contact is inserted inthe pin contact-receiving hole. Thus, the distal end of the pin contactenters between the movable contact and the fixed contact and presses themovable contact to separate the movable contact from the fixed contact.In contrast, when the pin contact is withdrawn from the pincontact-receiving hole, the movable contact abuts the fixed contactthereby to be electrically connected to the fixed contact. Accordingly,the receptacle has a switching function.

[0046] In addition, the receptacle may be disposed on a printed wiringboard and fixed to a ground pattern on the board by solder.

[0047] According to the invention of (2), the first reentrant of the pincontact holder is fitted in the first protrusion of the secondreceptacle housing, thereby to connect the plug to the receptacle. Thus,the first protrusion and the first reentrant are specified in shape sothat the connector can prevent any external antennas of othermanufacturers from being connected to the receptacle.

[0048] In addition, the plug can be connected to the receptacleindependently of the posture of the plug because it is not required tocombine a key and a key groove like conventional cases. On this account,the plug can be readily connected to the receptacle.

[0049] (3) The connector according to (1) or (2), wherein saidreceptacle includes elastically-deformable first pressing piecesprotruded from an inner surface of the shell-receiving hole of the firstreceptacle housing,

[0050] wherein an annular groove portion is formed in an outerperipheral surface of the shell of said plug, and

[0051] whereby the first pressing pieces of said receptacle areelastically deformed and engaged with a groove portion of said plug whensaid plug is plugged in said receptacle.

[0052] According to the invention of (3), the connector has a half-lockstructure to hold the plug in the receptacle by engaging the firstpressing pieces with the annular groove portion. Therefore, the plug canbe inserted in and drawn from the receptacle readily.

[0053] (4) The connector according to (3), where in the secondreceptacle housing is sandwiched between the first pressing pieces.

[0054] According to the invention of (4), the plug can be held by thereceptacle more reliably because the first pressing pieces are disposedso as to sandwich the second receptacle housing.

[0055] (5) The connector according to (4), wherein said receptacleincludes second pressing pieces protruded from an outer peripheralsurface of the second receptacle housing, and whereby the secondpressing pieces of said receptacle are elastically deformed to steadythe shell of said plug from its inside when said plug is plugged in saidreceptacle.

[0056] (6) The connector according to any one of (1) to (5), whereinsaid receptacle includes a fixed contact and an elastically-deformableelastic contact abutting the fixed contact, and

[0057] whereby the pin contact penetrates through the pincontact-receiving hole and presses the elastic contact to separate theelastic contact from the fixed contact when the pin contact is pluggedin the pin contact-receiving hole.

[0058] (7) The connector according to any one of (1) to (6), whereinsaid plug is connected to an external antenna for wireless LAN.

[0059] (8) The connector according to any one of (1) to (6), whereinsaid plug is connected to an external antenna for high-speed wirelessLAN standardized under IEEE 802.11a.

BRIEF DESCRIPTION OF THE DRAWINGS

[0060]FIG. 1 is a perspective sectional view showing a connectoraccording to a first embodiment of the present invention;

[0061]FIG. 2A is atop view of a plug according to the embodiment;

[0062]FIG. 2B is a longitudinal sectional view of the plug according tothe embodiment;

[0063]FIG. 2C is a bottom view of the plug according to the embodiment;

[0064]FIG. 2D is a transverse sectional view of a receptacle accordingto the embodiment;

[0065]FIG. 2E is a longitudinal sectional view of the receptacleaccording to the embodiment;

[0066]FIG. 3 is an exploded perspective view of main parts constitutingthe receptacle according to the embodiment;

[0067]FIG. 4 is a perspective view of the appearance of the receptacleaccording to the embodiment;

[0068]FIG. 5 is a perspective sectional view showing a connectoraccording to a second embodiment of the present invention;

[0069]FIG. 6A is a top view of a plug according to the embodiment;

[0070]FIG. 6B is a longitudinal sectional view of the plug according tothe embodiment;

[0071]FIG. 6C is a bottom view of the plug according to the embodiment;

[0072]FIG. 6D is a transverse sectional view of a receptacle accordingto the embodiment; and

[0073]FIG. 6E is a longitudinal sectional view of the receptacleaccording to the embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0074] The embodiments of the invention will be described below inreference to the drawings. In the description below on the embodiments,the same components are indicated by the same symbols and thedescription thereof is omitted or simplified.

[0075] [First Embodiment]

[0076]FIG. 1 is a perspective sectional view of a connector according toa first embodiment of the invention.

[0077] The connector has a plug 1 connected to an antenna through acoaxial cable 10, and a rectangular parallelepiped receptacle 2 whichthe plug 1 is to be put in and removed from.

[0078] The receptacle 2 is mounted on a side face of a notebook-sized PC(not shown), and the plug 1 is connected to an antenna for high-speedwireless LAN standardized under IEEE 802.11a. When the plug 1 isconnected to the receptacle 2, the connector can transmit and receiveradio waves with an external antenna.

[0079] The coaxial cable 10 includes: a core wire 10A as an insideconductor extending in its axial direction; an insulator 10B forcovering the core wire 10A, which is formed from polyethylene or thelike; a braided wire 10C as an outside conductor provided outside theinsulator 10B and extending in its axial direction; and an insulator 10Dfor covering the braided wire 10C.

[0080]FIG. 2A is a top view of the plug 1, FIG. 2B is a longitudinalsectional view of the plug 1, and FIG. 2C is a bottom view of the plug1.

[0081] The plug 1 includes: a cylindrical shell 12 having an outerdiameter d connected to the coaxial cable 10; a pin contact 11 connectedto the core wire 10A of the coaxial cable 10; and an insulative pincontact holder 13 provided inside the shell 12 for keeping the pincontact 11 on the central axis of the shell 12. In other words, theshell 12 and pin contact 11 are disposed concentrically.

[0082] The pin contact 11 has a columnar form with a small outerdiameter on the side of a distal end thereof, and a columnar form with alarge outer diameter on a proximal end side thereof. More specifically,a step is formed between the distal end and proximal end of the pincontact 11.

[0083] Furthermore, the distal end of the pin contact 11 is shaped intoa conical form. The pin contact 11 has an arc-shape groove formed on theproximal end side, and the core wire 10A of the coaxial cable 10 isfixed in the groove by solder.

[0084] A through-hole into which the pin contact 11 is inserted isformed in the pin contact holder 13. The through-hole has a large innerdiameter on the side of a distal end thereof and a small inner diameteron a proximal end side thereof. More specifically, a step is formedbetween the distal end and proximal end of the through-hole. When thepin contact 11 is inserted into the through-hole of the pin contact fromthe proximal end side of the through-hole of the pin contact holder 13,the step of the pin contact 11 engages the step of the through-hole,whereby the pin contact is held there.

[0085] The pin contact holder 13 has a columnar first protrusion 13Aformed on its distal end surface.

[0086] The shell 12 has an annular groove portion 1B formed in the outerperipheral surface thereof on the side of the distal end of the shell.

[0087] The shell 12 has notches formed in positions opposed to eachother nearly in the middle of the outer peripheral surface of the shell12. One of the notches is a protruding piece 1C protruding toward theinside of the shell, and the other is a bendable bending piece 1D.Therefore, the pin contact holder 13 is inserted into the shell 12 fromthe proximal end side of the shell until the holder 13 abuts theprotruding piece 1C. Then by bending the bending piece 1D inwardly, thebending piece 1D engages the pin contact holder 13. The pin contactholder 13 is thus held by the shell 12.

[0088] Also, the coaxial cable 10 is inserted into the shell 12 on theproximal end side of the shell. On the side of a distal end of thecoaxial cable 10, the insulator 10D is peeled off so that the braidedwire 10C is exposed. In a distal end portion of the portion where thebraided wire 10C is exposed, the braided wire 10C and the insulator 10Dare peeled off and thus the core wire 10A is exposed.

[0089] The exposed portion of the core wire 10A is fixed on the proximalend side of the pin contact 11. Further, an insulative tube ferrule 15is mounted between the exposed portions of the braided wire 10C andinsulator 10B. The exposed portion of the braided wire 10C is clamped onthe proximal end side of the shell 12. Therefore, the exposed portion ofthe braided wire 10C is pinched on the proximal end side of thecylindrical shell 12 and electrically connected to the shell 12.

[0090] The connecting portion of the plug 1 and coaxial cable 10 iscovered by a boot 10E as an insulating protective cover. Therefore, theplug 1 is put in and removed from the receptacle 2 by grasping the boot10E.

[0091]FIG. 2D is a transverse sectional view of the receptacle 2, andFIG. 2E is a longitudinal sectional view of the receptacle 2.

[0092] The receptacle 2 includes: a first receptacle housing 21 having ashell-receiving hole 2B into which the shell 12 of the plug 1 isinserted; and a second receptacle housing 26 which is provided insidethe shell-receiving hole 2B and has a pin contact-receiving hole 2A intowhich the pin contact 11 is inserted.

[0093] The shell-receiving hole 2B of the first receptacle housing 21has an inner diameter D which is slightly larger than the outer diameterd of the shell 12. An annular groove is formed between theshell-receiving hole 2B and the pin contact-receiving portion 22. Theannular groove and the pin contact-receiving hole 2A are formed onconcentric circles.

[0094] A first ground shell 24 extending along its axial direction isprovided in the inner surface of the shell-receiving hole 2B.

[0095] The second receptacle housing 26 includes: a cylindrical secondground shell 25 extending along the axial direction of theshell-receiving hole 2B; and the pin contact-receiving portion 22provided in the distal end of the second ground shell 25 and having thepin contact-receiving hole 2A.

[0096] A first reentrant 21A in which the first protrusion 13A is to befitted is formed in the distal end surface of the pin contact-receivingportion 22. The pin contact-receiving hole 2A is formed in the center ofthe first reentrant 21A. Elastically-deformable second pressing pieces25C, 25D which protrude outwardly are provided on the second groundshell 25.

[0097] Inside the second ground shell 25, there are provided a fixedcontact 23B extending along the axial direction of the second groundshell 25, and an elastically-deformable and movable contact 23A urgedtoward the fixed contact 23B.

[0098]FIG. 3 is an exploded perspective view of the first ground shell24, second ground shell 25, fixed contact 23B, and movable contact 23A,which constitute the receptacle 2.

[0099] The fixed contact 23B is shaped like a plate, and includes aproximal end portion 235 fixed on a printed wiring board (not shown) bysolder or the like and a distal end portion 234 which a bending piece233 of the movable contact to be described later abuts.

[0100] The movable contact 23A is formed from a leaf spring, andincludes a proximal end portion 232 fixed on the printed wiring board(not shown) by solder or the like and a distal end portion 231 curved sothat it becomes closer to the fixed contact 23B towards the distal endthereof.

[0101] The distal end portion 231 of the movable contact 23A is locatedon the route which the pin contact 11 is passed through. A portion nearthe distal end of the distal end portion 231 is bent toward the fixedcontact 23B and therefore it is a bending piece 233 abutting the fixedcontact 23B.

[0102] The second ground shell 25 is conductive and has a cylindricalform on the side of its distal end portion and a U-shaped form in crosssection on the proximal end side thereof. On the distal end side of thesecond ground shell 25, there is provided one pair of second pressingpieces 25C, 25D disposed opposed to each other The second pressingpieces 25C, 25D are elastically deformable and extending toward theoutside of the second ground shell 25. The second ground shell 25 isfixed to the printed wiring board (not shown) by solder or the like onthe proximal end side and grounded.

[0103] The above-described first ground shell 24 is conductive and has aU-shaped form in cross section. The first ground shell 24 has a flange(brim) formed on the proximal end side. The flange is fixed to theprinted wiring board (not shown) by solder or the like and grounded.

[0104] Also, on the first ground shell 24 there is a pair ofelastically-deformable first pressing pieces 24A, 24B by which thesecond receptacle housing 26 is sandwiched. The first pressing pieces24A, 24B are curved at curved portions 241, 242. The curved portions241, 242 are stuck out inwardly (see FIG. 2).

[0105] The movable contact 23A, fixed contact 23B, second ground shell25, and first ground shell 24 are press-fitted into the first receptaclehousing 2l and integrated. More specifically, the movable contact 23Aand the fixed contact 23B are press-fitted into the second ground shell25 from the proximal end side, and the second ground shell 25 ispress-fitted into the first ground shell 24 from the side of the distalend.

[0106]FIG. 4 is a perspective view of the appearance of the receptacle2.

[0107] The first receptacle housing 21 of the receptacle 2 has twothrough-holes 20A formed on both sides of the shell-receiving hole 2B.Further, inside the first receptacle housing 21, there are providedsquare nuts 20B. The receptacle 2 is fixed to a side panel 4 of a PC byinserting screws 3 as fastening means into the respective through-holes20A and screwing the screws 3 in the respective square nuts 20B.

[0108] Now, the procedure of connecting the plug 1 to the receptacle 2will be described.

[0109] First, the distal end of the shell 12 of the plug 1 is alignedwith the shell-receiving hole 2B of the receptacle 2 and the plug 1 isinserted into the receptacle 2. Then, the pin contact 11 of the plug 1is guided into the pin contact-receiving hole 2A of the receptacle 2.When the plug 1 is further inserted continually, the first protrusion13A of the pin contact holder 13 is fitted in the first reentrant 21A ofthe pin contact-receiving portion 22. The plug 1 is thus connected tothe receptacle 2.

[0110] Further, the curved portions 241, 242 of the first pressingpieces 24A, 24B of the receptacle 2 are elastically deformed and engagedwith the groove portion of the plug 1. Concurrently, the second pressingpieces 25C, 25D of the receptacle 2 are elastically deformed to steadythe shell 12 of the plug 1 from the inside.

[0111] Also, the pin contact 11 is inserted into the pincontact-receiving hole 2A. Thus, the distal end of the pin contact 11enters between the movable contact 23A and the fixed contact 23B andpresses the movable contact 23A to separate the movable contact from thefixed contact 23B. In contrast, when the pin contact 11 is withdrawnfrom the pin contact-receiving hole 2A, the movable contact 23A abutsthe fixed contact 23B thereby to be electrically connected to the fixedcontact. Accordingly, the receptacle has a switching function.

[0112] Thus, the first protrusion 13A and the first reentrant 21A arespecified in shape so that the connector can prevent any externalantennas of other manufacturers from being connected to the receptacle.

[0113] In addition, the plug 1 can be connected to the receptacle 2independently of the posture of the plug 1 because it is not required tocombine a key and key groove like conventional cases. On this account,the plug can be readily connected to the receptacle.

[0114] Grooved notches are formed on distal end side and proximal endside of the periphery of the pin contact holder respectively. Thegrooved notches are engaged to the cylindrical shell to hold the pincontact holder in the cylindrical shell. [Second Embodiment]

[0115] The embodiment is different from the first embodiment in theconfigurations of the pin contact holder 14 and pin contact-receivingportion 22.

[0116]FIG. 5 is a perspective sectional view showing a connectoraccording to the second embodiment of the invention.

[0117]FIG. 6A is a top view of the plug 1, FIG. 6B is a longitudinalsectional view of the plug 1, and FIG. 6C is a bottom view of the plug1. FIG. 6D is a transverse sectional view of the receptacle 2, and FIG.6E is a longitudinal sectional view of the receptacle 2.

[0118] In the distal end surface of the pin contact-receiving portion22, there is formed a columnar second protrusion 22A. The pincontact-receiving hole 2A is located in the center of the secondprotrusion 22A.

[0119] In the distal end surface of the pin contact holder 14, there isformed a second reentrant 14A in which the second protrusion 22A is tobe fitted.

[0120] Now, the procedure of connecting the plug 1 to the receptacle 2will be described.

[0121] The second reentrant 14A of the pin contact holder 14 is fittedto the second protrusion 22A of the pin contact-receiving portion 22.Therefore, the plug 1 is connected to the receptacle 2. Thus, the secondreentrant 14A and the second protrusion 22A are specified in shape sothat the connector can prevent any external antennas of othermanufacturers from being connected to the receptacle 2.

[0122] The invention is not limited the above-described embodiments, andit includes the modifications and improvements which are made within ascope such that the object of the invention can be achieved.

[0123] For example, the connector of the present invention may have thefunction of wireless LAN and may be used for a notebook-sized PC or aPDA capable of switching between its external antenna and internalantenna.

[0124] The connector of the present invention can provide the followingadvantages.

[0125] The first protrusion of the pin contact holder is fitted in thefirst reentrant of the second receptacle housing, thereby to connect theplug to the receptacle. Thus, the first protrusion and the firstreentrant are specified in shape so that the connector can prevent anyexternal antennas of other manufacturers from being connected to thereceptacle.

[0126] In addition, the plug can be connected to the receptacleindependently of the posture of the plug because it is not required tocombine a key and a key groove like conventional cases. On this account,the plug can be readily connected to the receptacle.

What is claimed is:
 1. A connector comprising: a plug connected to anantenna through a coaxial cable; and a receptacle which said plug is tobe put in and removed from; wherein said coaxial cable including aninside conductor extending in its axial direction, and an outsideconductor provided outside the inside conductor and extending in itsaxial direction; wherein said plug including a cylindrical shellconnected to the outside conductor of said coaxial cable, a pin contactconnected to the inside conductor of said coaxial cable, and aninsulative pin contact holder provided inside the shell for holding thepin contact on a central axis of the shell; wherein said receptacleincluding a first receptacle housing having a cylindricalshell-receiving hole in which the shell of said plug is to be plugged,and a second receptacle housing provided inside the shell-receiving holeand having a pin contact-receiving hole in which the pin contact is tobe plugged; wherein a first protrusion is formed in a distal end of thepin contact holder; and wherein a first reentrant in which the firstprotrusion is to be fitted is formed in a distal end of the secondreceptacle housing.
 2. A connector comprising: a plug connected to anantenna through a coaxial cable; and a receptacle which said plug is tobe put in and removed from; wherein said coaxial cable including aninside conductor extending in its axial direction, and an outsideconductor provided outside the inside conductor and extending in itsaxial direction; wherein said plug including a cylindrical shellconnected to the outside conductor of said coaxial cable, a pin contactconnected to the inside conductor of said coaxial cable, and aninsulative pin contact holder provided inside the shell for holding thepin contact on a central axis of the shell; wherein said receptacleincluding a first receptacle housing having a cylindricalshell-receiving hole in which the shell of said plug is to be plugged,and a second receptacle housing provided inside the shell-receiving holeand having a pin contact-receiving hole in which the pin contact is tobe plugged; wherein a first reentrant formed in a distal end of the pincontact holder; and wherein a first protrusion which the first reentrantis to be fitted in is formed in a distal end of the second receptaclehousing.
 3. The connector according to claim 1 or 2, wherein saidreceptacle includes elastically-deformable first pressing piecesprotruded from an inner surface of the shell-receiving hole of the firstreceptacle housing, wherein an annular groove portion is formed in anouter peripheral surface of the shell of said plug, and whereby thefirst pressing pieces of said receptacle are elastically deformed andengaged with a groove portion of said plug when said plug is plugged insaid receptacle.
 4. The connector according to claim 3, wherein thesecond receptacle housing is sandwiched between the first pressingpieces.
 5. The connector according to claim 4, wherein said receptacleincludes second pressing pieces protruded from an outer peripheralsurface of the second receptacle housing, and whereby the secondpressing pieces of said receptacle are elastically deformed to steadythe shell of said plug from its inside when said plug is plugged in saidreceptacle.
 6. The connector according to claims 1 or 2, wherein saidreceptacle includes a fixed contact and an elastically-deformableelastic contact abutting the fixed contact, and whereby the pin contactpenetrates through the pin contact-receiving hole and presses theelastic contact to separate the elastic contact from the fixed contactwhen the pin contact is plugged in the pin contact-receiving hole. 7.The connector according to claims 1 or 2, wherein said plug is connectedto an external antenna for wireless LAN.
 8. The connector according toclaims 1 or 2, wherein said plug is connected to an external antenna forhigh-speed wireless LAN standardized under IEEE 802.11a.